In a multi-axis robot or the like which is used as an industrial robot, it is needed to emergently stop the robot so as to ensure safety in an emergency such as when a person and an obstacle gets in a working area and when operation failure occurs. IEC60204-1 and ISO10218-1 standards specify a plurality of stop patterns according to risk and working conditions (such as holding condition of objects) with regard to emergency stop of a robot.
As described above, it is extremely important to ensure safety of an industrial robot whose operation needs to be stopped in an emergency. Therefore, a robot control device is devised so as to prevent loss of control function due to a single failure of an element configuring a control circuit of a robot (Patent Document 1).